Multimode optical fibers have been introduced to increase transmission capacity in optical communications networks. Wavelength division multiplexing is utilized in these multi-channel fibers to enable the transmission of multiple optical modes in a single core or multiple distinct cores and help meet the explosive growth in the demands on network capacity. However, mode coupling, which causes the signals carried by specific modes to couple among each other, is a challenging technical issue in this context. A variety of approaches have been introduced to deal with the information scrambling resulting from this mode coupling.
Multiple-Input Multiple-Output communication in multimode optical fiber communication channels (MIMO) relies on coherent transmission with extensive fast forward error correction and electronic compensation to sort out scrambled signals. The principal states approach, as set forth in US PG Pub. No. 2014/0161439 A1, seeks to launch light into the normal modes of the optical system to limit mode coupling. Unfortunately, the components needed for generating, combining, and splitting these states are relatively complex and can be challenging to update and control.